In the medical field, it is a very common procedure, and often very necessary, to conduct a bleeding time test which measures the time required for the cessation of bleeding following a skin incision. This test is medically important because extended or prolonged bleeding time can be associated with, for example, a lack of or a great excess of platelets, abnormality of platelet function, coating of platelets by specific proteins or foreign materials or the action of certain drugs; e.g., aspirin.
Although the bleeding time test procedure was first described approximately ninety years ago, it did not receive general acceptance until the 1940's at which time the test's sensitivity was increased by making a skin incision on the forearm of the patient while maintaining a blood pressure cuff inflation to maintain venostasis at a standardized level. Using this procedure, a technologist simultaneously starts a stopwatch while making the incision. The emerging blood is then gently blotted every thirty seconds. The cessation of bleeding is defined as the time at which the blotting paper is no longer stained by the emerging blood. This amount of time is generally recorded to the nearest half minute.
Disposable bleeding time devices were first introduced in 1978 to facilitate automation and convenience. These devices improved the acceptance of the test by both the patient and the operator. However, the results were still subject to a variety of technical variables. Additionally, these devices were significantly more expensive than previous methods. This hindered the acceptance of such devices in many countries around the world. Importantly, different disposable devices evolved over time which were functionally quite dissimilar so that the results were not comparable. Thus, standardization remained an elusive goal in bleeding time testing.
An important bleeding time testing device is known as the TRIPLETT™ bleeding time testing device. This was named after the noted physician in blood coagulation and hematopathology, Dr. Douglas Triplett. This device is presently manufactured and sold by Helena Laboratories of Beaumont, Tex. This device met the goal of global standardization in bleeding time testing and utilizes advanced technology at a universally affordable price. This was a product that provided a new level of value to automated, disposable bleeding time devices. This TRIPLETT™ bleeding time testing device was designed to be user and patient friendly, virtually painless, and to mimic the incision motion of the original bleeding time method. The device makes a standardized surgical incision one millimeter deep by five millimeters long for accurate sensitive bleeding time testing. The blade automatically retracts after incisions so as to ensure safety. The device includes a large contact surface that distributes the downward force over a wider area of skin so as to reduce the potential for deep non-standardized cuts. This device is presently subject to patent protection under U.S. Pat. Nos. 5,662,672 and 5,733,300.
Various other U.S. patents have issued relating to such bleeding time testing devices. For example, U.S. Pat. No. 4,064,871, issued on Dec. 27, 1977 to W. J. Reno, teaches a bleeding time testing device that includes a housing having a surface with a slot defining a longitudinal opening into the housing. A blade is mounted within the housing for movement of the blade tip through and along the slot. Biasing springs are provided within the housing to urge the blade through the slot a predetermined distance and along the slot for a predetermined length to control the depth and length of an incision produced with the device. A trigger is provided to initiate movement of the blade along with a safety pin to prevent the inadvertent activation of the device.
U.S. Pat. No. 4,628,929, issued on Dec. 16, 1986 to Intengan et al., describes another type of retractable bleeding time testing device. This device includes a housing, a hammer mechanism pivotally positioned within the housing and having a cam surface, and a self-retracting shuttle supported within the housing and including a cam follower surface. The shuttle is operative to travel in a vertical direction by the movement of the cam surface along the cam follower surface and the force exerted on the shuttle by a first spring extending from the shuttle. A cutting blade is secured to the shuttle and is operative to move out of the housing to make the incision and then to self-retract into the housing. A second spring is operative to exert a force on the hammer to cause it to move along the cam follower surface and to cause the shuttle to travel downwardly thus causing the blade to travel out of the housing to make the incision. The second spring is also operative to move into a locked position to secure the blade within the housing after the blade has retracted back into the housing.
U.S. Pat. No. 5,031,619, issued on Jul. 16, 1991, to F. Pompei, describes a method for determining bleeding time which includes a cutting assembly and a member for providing a compensation factor as a function of the temperature of the patient. The cutting assembly provides an incision of predetermined dimensions for external bleeding therethrough. The compensation member measures temperature of the patient throughout the period of external bleeding and provides a compensation factor as a function of the sensed temperature.
One of the problems associated with the use of the TRIPLETT™ device is that the force applied to actuate the device is off-center from the location at which the blade emerges from the cutting surface. As such, variations of pressures applied to the device can occur. As a result, the bleeding time testing can have a lack of consistent testing. Angular deflections of the cutting surface can also occur by the off-center application of pressure to the actuator of such cutting device. As such, a need has developed for a device for actuating such bleeding time testing devices such that the pressure of actuation will be directly above the location of the incision.
U.S. Application Ser. No. 60/393,971, filed on Jul. 5, 2002, by the present applicant, describes a constant force actuator for a bleeding time testing device. This constant force actuator is externally applied to an existing bleeding time testing device. The bleeding time testing device includes a body having a bottom surface from which a cutting blade can emerge so as to carry out an incision. The body includes a switch pin actuator that extends outwardly of the top surface in the testing device body. The switch pin is movable between a pre-actuating position and an actuating position. A safety tab is removably positioned between the switch pin actuator so as to retain the switch pin actuator in its pre-actuating position. The safety tab is to be removable so as to enable the testing device to be actuated by moving the switch pin from the pre-actuating position to the actuating position. The cutting blade is cooperative with the switch pin actuator to move outwardly of the bottom surface of the body of the testing device when the switch pin is moved to the actuating position. In this provisional patent application, a constant force device is mechanically attached to the surface of the body of the bleeding time testing device. The constant force device has a housing that is mounted onto the top surface of the bleeding time testing device so as to extend parallel to the bottom surface of the device. A suitable spring clip is provided on the housing so as to allow the actuator housing to be affixed to the body of the bleeding time testing device. A slide frame is mounted on the housing so as to be in slidable relationship to the housing. The slide frame is movable between a pre-activated position to an activated position. In the pre-activated position, the slide frame has a surface which resides against the switch pin actuator in the pre-activated position. A spring is mounted so as to be cooperative with the slide frame so as to urge the slide frame to the actuated position. An actuator button is slidably mounted on the housing so as to be slidable in a direction transverse to the plane of the bottom surface of the bleeding time testing device. When the actuator button is depressed, the spring associated with the slide frame urges the slide frame in a horizontal direction parallel to the bottom surface of the bleeding time testing device and thereby moves the switch pin actuator from the pre-actuating position to the actuating position. The actuator button is positioned directly above the center line of the cutting blade during the incision procedure.
It is an object of the present invention to provide a skin incision device that will not make the incision until a controlled vertical force is applied against the subject tissue.
It is another object of the present invention to provide a skin incision device that removes the variations of force that are applied by different operators at the time the incision is performed.
It is another object of the present invention to provide a skin incision device which allows the actuation force to be easily altered by a modification of a spring for the purpose of providing different actuating forces.
It is a further object of the present invention to provide a skin incision device which can be assembled with no force required to load the components which interact to produce the incision.
It is a further object of the present invention to provide a skin incision device in which the blade is propelled by a designed controlled interaction of internal components which creates a slicing into, across and slicing out of subject tissue for the purpose of minimizing the trauma to the subject tissue.
It is another object of the present invention to provide a skin incision device which reduces the introduction of undesirable components of the skin tissue into the incision area and blood sample.
It is still a further object of the present invention to provide a skin incision device that promotes rapid healing of the incision location.
It is still another object of the present invention to provide a skin incision device which has a concurrent action at the incision which locks the device and prohibits the ability of the device to be reloaded for additional uses.